Various milling processes are known for the preparation of dispersions that can be selected as films and coatings for substrates. Two known milling processes are wet milling and dry milling. To optimize these processes agitator speeds are sometimes increased and there is used finer size grinding media.
Utilization of milling methods, such as ball milling, can be an extremely costly and a time consuming procedure, requiring in some instances 20 to 40 hours to complete and to provide dispersions that generate films with sufficient chemical, physical, and functional stability.
In one known milling method, there is selected a grinder, such as a ball mill, where an inclined or horizontal rotating cylinder is partially filled with ceramic balls, flint pebbles, and/or stainless steel balls, each of which grinds materials to the necessary fineness by friction and impact with the tumbling balls. An internal cascading effect reduces the material present to a fine powder, and where large to medium-sized ball mills are mechanically rotated on their axes. High quality ball milling processes are costly and may not be environmentally acceptable over extended usage in that grinding media residues result that need to be disposed of and that can contaminate the devices used and the materials being treated. Because of the high important speeds usually needed with ball milling there can be problems with the materials present to rotate along the direction of the cylindrical device resulting in no further grinding.
A planetary ball mill, smaller in size than common ball mills are mainly used in laboratories for grinding sample materials down to very small particle sizes. The grinding steel balls in the grinding container are subjected to superimposed rotational movements, with the differences in speeds between the balls and grinding containers producing an interaction between frictional and impact forces, which releases high dynamic energies.
In a number of known ball milling methods, once the particles reach a certain size they can re-combine at the same rate since they are being fractured, or do not fracture effectively, and therefore, do not reduce further in size. Thus, the manufacture of very fine particles by ball milling can require substantial efforts and there are also factors which consequently place limits on the minimum size of particles of active materials which can be achieved by such milling processes.
There is a need for processes that avoid the disadvantages of ball mills and ball milling processes.
Further, there is a need for economical processes where materials can be treated in a simple manner in the absence of ball milling.
Another need resides in providing processes wherein contaminates are avoided or minimized, and which processes are environmentally acceptable.
Yet another need resides in providing ball milling free and roll milling free processes for generating dispersions or coatings for substrates.
Additionally, there is a need for processes that avoid or minimize the formation of undesirable grinding media residues.
Also, another need resides in providing processes where dispersions with desirable and consistent characteristics are obtained in a direct economical manner, and that minimize the formation of contaminates.
Moreover, a further need relates to economical environmentally processes that produce dispersions with properties that enable the dispersions to be selected without further treatments, for the formation of xerographic components, such as intermediate transfer members, fuser rolls, donor rolls, pressure rolls, toner transfer belts and other roller surfaces, and where roll milling and ball milling are avoided, and resulting in components with excellent chemical, physical, and functional stability.
In addition, there is a need for the direct preparation of dispersions with desirable particle sizes that are more difficult to quickly achieve with ball milling, especially as this relates to the preparation of dispersions for xerographic belts and rolls, such as fuser belts, and intermediate transfer belts, and is cleaner (more environmentally acceptable) in that grinding media residues can be avoided or minimized.
There is a need for dispersions or mixtures prepared by mechanical blending, and which dispersions can be selected for the formation of intermediate transfer members with excellent break strengths as determined by their modulus measurements, which are readily releasable from substrates, and possess high glass transition temperatures, and improved stability with no or minimal degradation for extended time periods.
These and other needs and advantages are achievable in embodiments with the processes disclosed herein.